1. Field of the Invention
This invention pertains to a novel way of creating an anti-bacterial barrier at the female opening of a needleless valve when it is in its closed condition.
2. Description of the Prior Art
When a medical valve is in a closed condition, it is essential that bacteria be prevented from entering it. The most likely area of entry for bacteria resides at the interface between the movable piston which constitutes the moving element of the valve mechanism and the entry to the female luer portion of the body, which constitutes the static portion of the valve.
Prior art designs have provided for an elastomeric seal attached to, or integral with, the movable piston. As the piston is urged toward the inside of the valve body by the luer tip of a syringe or IV connector, this seal acts as a wiper seal against the inside surface of the female luer in the body. An exemplary prior art valve system is depicted in FIG. 1. It includes movable wiper seal 13 and return spring 15.
This wiper seal is effective in preventing bacterial contamination; however, it presents two problems. Both of the problems are associated with the fact that the wiper seal must remain in contact with the inside surface of the female luer taper of the body throughout its downward travel as the valve opens:
1. Since the inside diameter of the taper becomes smaller and smaller as the wiper seal travels downward, the frictional force on the wiper seal and therefore on the valve piston keeps increasing. This means that the return spring (which causes the piston to move back to its original position when the syringe or IV connector is disengaged from the valve) must be strong enough to overcome this resistance. This is undesirable because this increased spring resistance will be brought to bear against the male luer tip while the syringe or IV connector is attached to the valve and, unless these devices have a luer lock feature (which many IV connectors do not), it increases the risk of accidental disconnection (with its associated clinical problem of depriving the patient of a needed fluid and/or medication).
2. As the male luer pushes the top of the piston downward, it is desirable that fluid injection be possible as soon as possible and regardless of where the distal tip of the luer ends up stopping. If the inside surface of the female luer of the body were perfectly smooth, the wiper seal would prevent any fluid flow into the valve. In order to prevent this condition, the inside surface of the female luer is generally grooved. If the wiper seal remains in contact with this grooved surface for an extended period of time, the elastomer can take a set, assume a dimpled configuration and, at least temporarily, provide a less effective bacterial seal when the valve is allowed to close again.